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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Drummerboy on November 22, 2009, 10:01:08 PM
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Hello,
This morning, when i was using my A1200, a couple of times when the right button mouse was pressed, i listened a sound like " tack..tack" in the Speakers, but i not give importance. A few minutes ago, i hear again thats sound, then i start to suspect something is wrong, and after check with some Mods Player, Sids Player, and WHDLoad games and change of speakers, the results is the sound is very low, for can hear something was necesary to raise the volume to the max.
Another thing is, if you change in any Mod Player the Filter use, thats sound (tack tack) appears.
The questions is...
The sound chip are dying?
Somebody here, happened the same or similar thing?.
Comments, suggests, recomendations
best regards
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The capacitors are dying. They'll need to be replaced.
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The capacitors are dying. They'll need to be replaced.
hummm
Where is thats capacitors?
Its not necesary only change a Paula Chip?
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yep its the audio capacitors...very common problem with our beloved classic miggys !
Do a quick search here and you'll find all the info you need to get them replaced if you are handy with a soldering iron...if your'e not then hopefully youn have a friend that is :-)
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I've same problem, it's because black 0,5mmx1mm part (what ever it is) is broken near rca connector
I get "good" sound from composite
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I've same problem, it's because black 0,5mmx1mm part (what ever it is) is broken near rca connector
I get "good" sound from composite
Ok,
When you say composite, is from RF Output?
Then thats capacitors, give power to the Paula Chip with the RCA ouputs ?!
If its common this kind of damage, why happen this?
You know a have the strange or common practice if i dont use the computer for a few muinutes i turn off the monitor, but the started the computer, i use a C=1942 monitor in this A1200 Conected to Audio Monitor RCA inputs, can this damage the capacitors?, or i using a PCMCIA network card, has any relationship any of this things?
Anyway i ask this becouse in this things sometimes happen mistery facts.
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Ok,
Let see if somebody can help me showing where is the capacitors. Here any Pic if the Motherboard
And somebdy know what number of part is, and if is available obtain in anywhere electronics components store.
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Ok,
i found some answers to my own questions..
Apparently, the problem with this capacitors, its becouse theyre leak like the batterys!!.. yeah .. the nightmare continues!!!..
Then, the recomendations is replace for Non polarized capacitors.. theyre not leak.
Anyway i am using the A1200 for write this post, i will check if can see any leaked signal in any part in the motherboard .
if somebody has any idea, commment, answer to the asked questions or recomendation please let me know..
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Non-polarized capacitors leaks, too!
It is strongly recommended swap the original polarized units for this other type because the original circuit is an alternate current circuit. Common capacitors will last much more than those originally installed.
Capacitors leakage is less aggressive than battery leakage, but still corrode traces and can "pop" the audio pre-amplifier IC (a small IC near the audio out jacks).
The capacitors are the 22uF x25V (or more voltage) near the audio jacks.
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I've written plenty of detail on this subject in this article (http://amiga.serveftp.net/audio_repair.html). It describes the A4000 analogue audio stage, but the A1200 circuit is mostly the same. The main difference is the physical layout.
Replacement parts are available from the likes of Farnell, Radio Spares Digi-Key.
If you can't repair it yourself, I operate a comprehensive Amiga repair service from New Zealand. Contact details on the site mentioned above.
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Non-polarized capacitors leaks, too!
It is strongly recommended swap the original polarized units for this other type because the original circuit is an alternate current circuit. Common capacitors will last much more than those originally installed.
@rkauer
Just read your comment regarding capacitor polarisation. In this application that statement is simply not true. Bipolar capacitors would only be required if the applied frequency is low enough so that the reactive impedance of the capacitor becomes significantly higher than the impedance of the load you're driving, and the AC amplitude is high enough, therefore causing the capacitor to be momentarily reverse biased to a level high enough to cause damage.
In fact I do recall explaining the same detail in the past, refer to this thread (http://www.amiga.org/forums/showthread.php?t=34336).
If capacitive coupling of AC signals using polarised capacitors was indeed a problem, then pretty much every piece of analogue electronic equipment on the planet would be affected; they all use the same techniques.
Some rare occasions where you do actually require non-polarised capacitors for audio coupling include:
- 2-wire telephone circuits, as the 50V line polarity could be either way
- Speaker passive crossover networks, where the low frequencies, high voltages and low impedance loads concerned are actually an issue with coupling capacitors
Have a read on basic audio amplifier theories for more detailed explanations.
The electrolytic capacitors in question typically begin leaking due to poor long term stability of the electrolyte. For the same reason, many low quality capacitors of unknown brand are frequently seen leaking in modern electronic designs. For example, it's a common problem on the DC reservoir capacitors in some modern computer boards, often less than a year or two old. The parts are correctly polarised in relation to the DC supply, but they leak due to the unstable electrolyte.
That's why product from renowned manufacturers such as Panasonic and Rubycon are generally more expensive; because they've spent a good deal on research to obtain a stable chemical compound and have years of experience to verify it. Sometimes you do get what you pay for.
So when providing advice *PLEASE* do try to give correct advice and research the facts if you're unsure.
Let me know if you need clarification on anything I've mentioned.
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I've written plenty of detail on this subject in this article (http://amiga.serveftp.net/audio_repair.html). It describes the A4000 analogue audio stage, but the A1200 circuit is mostly the same. The main difference is the physical layout.
Replacement parts are available from the likes of Farnell, Radio Spares Digi-Key.
If you can't repair it yourself, I operate a comprehensive Amiga repair service from New Zealand. Contact details on the site mentioned above.
Great Article!!..
thats explain everything about this thing..
Congrax.
I found a Capacitors 22uF x 35v . (--- this can work right?
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I found a Capacitors 22uF x 35v . (--- this can work right?
That will work. I replaced mine with the original SMD type, only high quality Japanese variety as Castellen noted (Panasonic and Chemi-Con, both excellent).
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That will work. I replaced mine with the original SMD type, only high quality Japanese variety as Castellen noted (Panasonic and Chemi-Con, both excellent).
Ok..great!..then... now..Lets Work!!
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Couldn't you replace the electrolytic w/ tantalum ines, which (I think) don't leak
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Couldn't you replace the electrolytic w/ tantalum ines, which (I think) don't leak
They don't leak, they flash.
Taken from Wiki:
Tantalum capacitors possess very low electrical leakage (high leakage resistance), and will retain a charge for a long duration. They are also more tolerant of hot operating environments, unlike standard aluminium electrolytic capacitors. Tantalum capacitors are relatively expensive, particularly the military grades. They are not particularly tolerant of heavy charge and discharge currents, particularly those of a repetitive nature. Their effective series resistance (ESR) is quite high when compared to aluminium electrolytics.
As with all electrolytic capacitors, correct polarity must be observed otherwise the capacitor will depolarize and the dielectric oxide layer will be reduced back to the metal, reducing the resistance of the device and causing it to become very hot and possibly explode. Tantalum capacitors are less prone to "drying out", causing a decrease in capacitance as is often the case with aluminium electrolytic capacitors particularly when used in hot environments. They maintain their designed capacitance under such conditions over long periods (decades).
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The above notes about tantalums are indeed correct.
It's also worth pointing out that they will work fine for audio coupling and will be OK in the Amiga if you want to use them. The problems you might have is the mechanical mounting of them since the PCB pads for SMD electrolytics are different to those used by SMD tantalums.
Tantalums should generally not be used on DC power supply rails for AC decoupling. The reason is that the low equivalent series resistance of the tantalum capacitor results in a very high momentary inrush current when the power supply is turned on. The high current flow causes the capacitor to heat up internally, which can result in it going short circuit and sometimes exploding. Google 'explode' and 'tantalum' to find out more.
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Before working on your Amiga - try swapping your PSU for one that's known to be good.
One of my PSU's developed a fault which allowed ac to be passed through to my A600, causing a machine gun rat-tat-tat sound through the speakers (and graphical glitches/system crashes too).
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Ok,
I was checking inside and and the apparently the acid only was in the Capacitors base, but never put many atention to this compnentes in the A1200, and see i cant replace the componentes my self, becouse my soldering tool its not properly, then i be need do with any people have the right soldering tool.
Anyway, for now y clean the motherboard and the bad capacitors.
But here born a new thing!, becouse inside the A1200 i sew 2 more capacitors the same Rating, and other capacitors, diferent number rating, but the same look, then the Question is..
Exist any damage report in this other capacitors?..
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Before working on your Amiga - try swapping your PSU for one that's known to be good.
One of my PSU's developed a fault which allowed ac to be passed through to my A600, causing a machine gun rat-tat-tat sound through the speakers (and graphical glitches/system crashes too).
Humm.. intersting.. and any problem with the sound?..
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Ok,
I was checking inside and and the apparently the acid only was in the Capacitors base, but never put many atention to this compnentes in the A1200, and see i cant replace the componentes my self, becouse my soldering tool its not properly, then i be need do with any people have the right soldering tool.
Anyway, for now y clean the motherboard and the bad capacitors.
But here born a new thing!, becouse inside the A1200 i sew 2 more capacitors the same Rating, and other capacitors, diferent number rating, but the same look, then the Question is..
Exist any damage report in this other capacitors?..
Definitely! Replace them all. On the few boards I've repaired, they seem to fail somewhat randomly (some worse than others). If the leakage is minor it might not be visible (yet), so IMHO go ahead and clean around all of them until you can get it repaired.
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One of my PSU's developed a fault which allowed ac to be passed through to my A600, causing a machine gun rat-tat-tat sound through the speakers (and graphical glitches/system crashes too).
Humm.. intersting.. and any problem with the sound?..
Take a guess! :hammer:
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Definitely! Replace them all. On the few boards I've repaired, they seem to fail somewhat randomly (some worse than others). If the leakage is minor it might not be visible (yet), so IMHO go ahead and clean around all of them until you can get it repaired.
Ok, i will do, replace all them ..
thanks
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One of my PSU's developed a fault which allowed ac to be passed through to my A600, causing a machine gun rat-tat-tat sound through the speakers (and graphical glitches/system crashes too).
Take a guess! :hammer:
With other PSU, the same failure!..
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That's a discussion which may solve your problems: let's change those capacitors! (http://eab.abime.net/showthread.php?t=47326)